Multi-well Gas Lift Opt

1. Overview

The Multi-well Gas Lift Optimizer is designed to allocate limited lift gas resources across a group of wells to maximize total oil production. Rather than optimizing each well in isolation, this module considers the diminishing returns of injecting gas into individual wells and redistributes injection volumes to achieve the best area-wide production uplift.

This tool simplifies what would otherwise be a complex, iterative process involving manual analysis of each well's gas lift performance curve. By automating the generation of individual well optimization curves and combining them into a system-level optimization, the tool helps engineers:

• Prioritize wells with the highest incremental oil rate per unit of injected gas
• Plan efficient gas injection strategies within a gas supply limit
• Compare the impact of different gas availability scenarios on total production

Portfolio-wide Optimization

Think of this feature as a “portfolio optimizer” for gas lift — instead of maximizing just one well, you’re maximizing your entire field.

2. Prerequisites

Before using the Multi-Well Gas Lift Optimizer, ensure the following for each well:

• The well has been set up with the appropriate wellbore configuration.
• At least one configuration uses Gas lift as the selected Artificial Lift method.
• A valid Rates and Pressures source date is selected during a period when the well is operating under Gas Lift.

These inputs are essential to generate accurate gas lift performance curves for each well.

3. Workflow Steps

3.1. Initialize Optimization Variables

3.1.1. Maximum Group Combined Injection Rate

This input allows users to specify the maximum available gas injection rate for the group of gas-lift wells.

• By default, the system automatically aggregates (sum) the current gas lift rates of all wells to define the combined maximum injection rate.
• Users can manually override this value by clicking the calculator icon and entering a custom rate.

3.1.2. Minimum Injection per Well

This variable represents the critical gas rate required to prevent liquid loading in each well. Users can select a different correlation that best fits their analysis need.

• By default, the minimum gas injection rate is set using Turner correlation.
• Selecting None removes the minimum injection constraint entirely, allowing wells to become liquid loaded during the optimization run
• Choosing User Defined enables users to manually specify a minimum gas injection rate that will be applied uniformly across all wells.

3.1.3. Critical Rate Depth

When using a correlation to calculate the minimum gas injection rate for each well, users can specify the point or depth along the well configuration where the critical gas rate should be evaluated.

• By default, the calculation is performed at the End of Tubing.

3.1.4. Reservoir Pressure Resource

The Reservoir Pressure Resource is used to generate the IPR/VLP curves and determine their intersection, which defines the operating point for gas-lifted wells.

• By default, Automatic is selected, meaning the reservoir pressure is sourced from the average reservoir pressure calculated in the Flowing Material Balance module for each well.
• History Matching uses the average reservoir pressure from the simulation results in the Numerical Model module.
• Users may also choose Fetch from IPR if they have manually generated IPR/VLP curves for each well in the Nodal Analysis module.

3.1.5. BHP Correlation for VLP

The selected BHP correlation will be applied universally to all wells, calculating BHP from the surface down to the top of perforation. This calculated pressure is then used to generate the VLP curve. The default correlation is Hagedorn & Brown.

3.1.6. Rates and Pressures

The production data (rates and pressure) on a specific date is used to generate the IPR/VLP curves.

• Last Daily Production Data Values automatically selects the most recent available production data for each well.
• Fetch from IPR/VLP uses the values from manually generated IPR/VLP curves within the Nodal Analysis module for each well.

3.2. Optimize Multi-well Gas Lift

To run the multi-well gas lift optimization, click the OPTIMIZE ALL WELLS button (figure below). The process will execute shortly, and the results will be displayed in a table.

4. Optimization Principles

The underlying principle of multi-well optimization is marginal uplift per unit gas injected. Wells that produce a steep increase in oil rate with a small increase in gas are prioritized over wells showing diminishing returns.

The optimizer follows these principles:

• Stage 1: Inject gas where marginal oil gain per Mscf is highest.
• Stage 2: Continue until the marginal gain drops or the gas limit is reached.
• Stage 3: Stop injecting when additional gas yields minimal or no production increase.

This avoids over-injecting gas into inefficient wells and ensures maximum field-level efficiency.

5. Example Case: Eagle Ford Wells

On a blank project, users can load the example wells using MASS UPLOAD -> EXAMPLES feature. This will load 11 wells into your project with production data and multiple artificial lift configurations, including Gas Lift.

Important

Not all wells have their last configuration as Gas Lift. This is important reminder because we will use default optimization setting where rate and pressure values will be pulled from the last production data which corresponds to the last configuration used in the well.

5.1. Initialize Optimization Variables

Once the wells are ready, navigate to the Multi-well Gas Lift Opt module from the left navigation panel, then proceed to create a new optimization scenario (click on ADD MULTIWELL GAS LIFT OPTIMIZER) and include all wells in this project. In this case, we use the default settings for the optimization variable initialization.

5.2. Multi-well Gas Lift Optimization Results

Once the multi-well optimizer has been created and initialized, navigate to the Gas Lift Optimization tab and click OPTIMIZE ALL WELLS to execute the optimization run. It will evaluate the optimal gas allocation for each well and display the results in a dynamic table.

Users can customize what outputs are shown by selecting the desired checkboxes in the parameter list on the left. We implement color scaling to help quickly identify performance across wells. In the bottom-left of the page, you'll see a "Total Current Oil Rate Uplift", this summarizes the total potential production gain from redistributing gas injection across wells.

Note

A value of 0 in the table indicates that the well was not optimized. This happens, in this case, because the well's last production data corresponds to a configuration not a Gas Lift.